An EL device typically comprises a light transmissive electrode, a first dielectric layer, overlying the electrode, a phosphor layer overlying the first dielectric layer, a second dielectric layer overlying the phosphor layer and a second electrode overlying the second dielectric layer. The applied electric field between the electrodes produces light emission through the light transmissive electrode at wavelengths characteristic of the phosphor material. If one or both electrodes are patterned to form picture elements an image can be displayed on such a device corresponding to a time-varying pattern of electrical voltages applied to the electrodes.
These devices are finding increased utility in applications such as data displays because they are compact and rugged and have comparatively low power consumption. However, the phosphor layer forms an optical waveguide which traps a portion of the generated light which is then reabsorbed or transferred to the periphery of the display. This effect reduces the display brightness. It would be desireable to have an electroluminescent device and a method of making same which reduced or eliminated this problem.